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C. RALEIGH AND W. V. D. KELLEY, coLoR PHOTOGRAPHY.

APPL-ICATION FILED DEC. 20l |916.

' Patented Dec. 16,1919.

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N A'UNITED sTATEs PATENT oEnioE.

l CHARLES RALEIGH, OF JERSEY CITY, NEW JERSEY, lAND WI'JLIAIM V. D.KELLEY, OF

BROOKLYN, NEW YORK, ASSIGNORS, BY MESNE ASSIGNMENTS, TOy PRIZMA INCOR- YPORATED, A CORPORATION OF MAINE.

Be it known that we, CHARLES RALEIGH, a subject of theKing of GreatBritain, and WILLIAM V. D. KELLEY, a citizen -of the United States,residing at Jersey City,`

county of Hudson, Statehof New Jersey, and Brooklyn, county of Kings,State of New York, respectively, have invented certain new and usefulImprovements -in Color Photography, of which the following is a full,clear, and exact specification. VThis invention relates to photographyin colors, and has particular reference to the reproduction of motionpictures in natural colors. The object of the invention is to provide amethod, color screen, and image produced thereby, which while'iilteringthe light to produce the various color value records on theemulsion-will` also asclosely as possible approximate the conditions ofa colorless 'transparency in simultaneously passing the light.

In French Patent No. l479,921, granted February 2,9, 1916, there isdisclosed a method, screen, and image, wherein an ex-` posure to whitelight and a color value record are superposed on the same section ofemulsion, whereby the several component color records of the cycle areintensied or leveled without destroying the difference in color value.According to said patent, there is a clear section associated with eachfundamental color filter section 'so that each emulsion section isexposed both to\the color section to, obtain the color value record, andto the clear or intensifying sector to obtain black and white values. Bysuch apparatus and method, the resulting pictures are soft and pleasingin color, and owing to having been intensified, are as complete indetail and depth as though an ordinary exposure made without colorlters. Y

This invention relates to the same subject, but embodies an improvementin the method,

screen, and image, whereby a sudden transition from the color section tothe clearI section, or vice versa, -is avoided by means of a` graduatedscreen or filter, each section preferably uniformly shading frompractically clear (or open) to the full color depth for that section, orthe color uniformly weakens lto white or clear.- This is useful ingraduat-f ing the proportions o f color and clear in "each section, andalso in balancing two,A

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three, four or'more sections. The exposure more of the screensectionsmay be made-in this way, although it is preferable that all bel so made..Suicient color value differences A are thereby obtained between theimages of a series so that the original colors are .reproduced whenprojected; less light is required to obtain a good exposure than withknown screens made up of uniform solid color; the series of pictures onthe film are very much more uniform in appearance and'intensity thanwhere solidl screen colors are used; andv the'light admitted to theemulsion section at all times favors the desired color value.

The screen carrying the filters ismovable specification of LettersPatent. Patented Dc. 16, 1919.

Application led December 20, 1916. Serial No. 137,943. I

for both still and motion color photography.

The simplest form is a revolving screen as herein illustrated, but itmay reciprocate, or be embodied 'on an endless band, or in any otherway, so that the filter screens move Figure 1 is a perspective view of afour color screen embodying one` form of the, invention, and

Fig. 2 is a cross-section. The invention can be carried out in variousways, of which only a few examples are mentioned herein. For example,the filters can .be made of gelatin and colored or dyed so that thecolor desired is of f'ull depth at `during the period of exposure. In athree f one end and shades off tofpractically no color, A

or but very little color', at-.the other end.

Examples of such shading are shown in Fig. l, wherein B is the bluesection which is darkest at the bottom and shades to practically nocolor at the top, R is the red section shown as darkest atithe top andshading to practically no color at the bottom, G is the green sectionshown as darkest at the top and shading to practically no color at thebottom, while Y is the yellow section which is darkest at the right andshading to practically no color at the upper edge. K are the opaquesections between each lter section, which cover the emulsion while it isbeing changed.

Another filter can be made of pot-metal glass, or flash glass, that is,lglass having color throughout its structure, or on one surface. Theseare then ground down to a wedge shape, so that the density of the coloris greatest at the thick end and less at the thin end. Effects due todiffraction or re fraction, owing to the wedge shape of such filters,can be avoided by applying thereto similar but reversed wedge shapefilters of l the same kind of clear glass, so that the whole filter hasa uniform indexk of refraction, but still is graduated as to color,being heaviest at -one end and with little or no color at the other, asin Fig. 2.

Also, in case it is desired to compensate for a preponderance of colorrays in the light, as for instance excessive blue violet in arc light,the clear portions can lbe given a graduated yellow tint, either o'fgraduated yellow colored gelatin, densest at the clear portion of thefilter, or by using a wedge shape colored glass similarly disposed.Anexample of a wedge shaped glass filter section compensated for yellowis shown in Fig. 2, in which M represents the color section ground downto a point at l?, and having combined therewith a compensating reverselyarranged wedge at the thick end opposite the thin end of the colorsection. Thus M may be a section of any 'one of the filters B, R, G, Y,above described, and O a section of a yellow colored compensating filterassociatedv therewith for correcting a preponderance of blue violet inarc light. This is especially desired in casethe panchromatic filmemulsion is over sensitive to violet rays, as is frequently the case. Itwill be understood that where yellow is used in this manner it is merelyas a corrective means, and not for color values, and while preferablyused on all the filter sections to correct for color need notneeessarily be so used. It will be obvious that screens embodying thisinvention may be made up in many ways other than herein explained, andthat they may be variously mounted on movable supports either rotary, orreciprocating, or movable bands, without departing from the scope of theinvention.

It will be understood that the manner of applying the broad features ofthis invention is not restricted to the specific forms herein described.For example, it may be desired to vary the screen section from fullcolor at one end to no color in the middle and then to` full color atthe other end, or the full color may be in the middle and shade towardeach end to no color, or the clear sections may merge from one side toone fundamental color and from the other side to another fundamentalcolor. rllhe invention can be used both in taking and proj ecting. Thecolor value negatives obtained in taking are developed and printed inthe usual manner, and then projected either with the same screen used intaking, or with a correspondingly colored screen without the clearportions.

t will be seen that such arrangements and many others can readily bemade without departing from the scope of the appended claims.

vWhat we claim is l. The method of recording a color value, whichconsists in exposing the same panchromatic emulsion to light varyingcontinuously during the exposure between a fundamental color componentand substantially white light.

2. The method of recording a color value, which consists in exposing thesame panchromatic emulsion to light varying oon tinuously during theexposure between a fundamental color component and light y compensatedto be substantially free of preponderating color constituent.

3. The method of recording a color value, which consists in exposing thesame panchromatic emulsion to light varying continuously during theexposure between a fundamental color component and white lightcompensated for blue violet contained therein. y A

4. The step in making photographic records, which consists in exposingeach of a predetermined succession of panchromatic emulsion sectionsthrough a different color filter, each color filter continuously varyingbetween a predominant component and light substantially free ofpreponderating color.

5. The step in making photographic records, which consists in exposingeach of a predetermined succession of panchromatic emulsion sectionsthrough a different color filter, each color filter continuously varyingbetween a predominant component and light compensated to besubstantially free of preponderant color constituent.

'6. The step in making photographic records, which consists in exposingeach of a succession of panchromatic emulsion sections through adifferent color filter, each color filter continuously varying between apredominant component and' light compensated by yellow for blue violet.

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7. In motion picture color photography employing a plurality of colorvalue images in recurring cycles, the step which consists in recordingeach image of a cycle by light varying continuously during the exposurebetween a fundamental color` component and light substantially free ofpreponderating color, the fundamental colors in each cycle formingsubstantially White.

8. In color photography, the method of increasing the density of arecord, Which consists in recording a fundamental color value Whilesimultaneously varying White light value.

9. In color photography, the method of increasing the density of arecord, which consists in recording a fundamental color value Whilecontinuously weakening said color value and increasing the black andWhite values.

recording a 10. In color photography, the method of increasing thedensity of a record, which consists in recording a fundamental colorvalue While continuously and inversely varying the relative intensity ofthe color and black and White values.

11. In color photography, the method of increasing the density of arecord in a given time7 which consists in recording the color values byconstantly decreasing a fundamental color and constantly increasingblack r and White Values.

In testnnony whereof We aiix our signa,u tures 1n presence of tWoWitnesses.

CHARLES RALEIGH. WILLIAM V. D. KELLEY.

' Witnesses:

FREDERICK N. EsHER, NEALE RANsoM.

